The present invention relates to a Stirling engine.
In general, in a Stirling engine which is disclosed, for example, in the U.S. Pat. No. 4,984,428, an expansion space is positioned adjacent to a heating portion and a thermal connection therebetween is established. Thus, the temperature in the vicinity of the expansion space becomes extremely high, which results in that the raw material and the structure of the expansion piston are restricted in order to prevent a short life of the expansion piston. Similar restrictions lie in a piston ring provided on an outer surface of the expansion piston.